Thirty students from Michigan fire departments, sheriff’s offices and other public safety agencies have spent the past two weeks learning about fire.

An old farmhouse served as a learning laboratory on Thursday for the fledgling fire investigators. Different rooms of the empty home south of Lansing were set on fire; the students had to figure out exactly how those fires were started.

Lenny Jaskulka is a specialist sergeant with the Michigan State police. He says there’s a lot to learn to become a certified fire scene investigator.

A Marathon Petroleum spokesman says no one was hurt after a fire at a refinery in Detroit.

Shane Pochard tells The Associated Press the fire started Saturday evening in one of the smaller tanks at the Marathon Petroleum refinery. He says the fire has been put out and the cause is being investigated.

Pochard says no employees or contractors were injured. He says Marathon Petroleum has conducted extensive air monitoring in the neighborhood where the refinery is located and the area is safe.

Some forensic science often used in police investigations is being called into question.

PBS' Frontline did an excellent series calling out the questionable science behind many arson cases.

In "Death by Fire" they showed how testimony from so-called fire experts led to the convictions of people for arson.

In one case, a potentially innocent man, Cameron Todd Willingham, was put to death in Texas based on questionable fire evidence.

Did Texas execute an innocent man?

Several controversial death penalty cases are currently under examination in Texas and in other states, but it's the 2004 execution of Cameron Todd Willingham -- convicted for the arson deaths of his three young children -- that's now at the center of the national debate.

Today, we hear the story of David Lee Gavitt from the Detroit Free Press. Gavitt, from Ionia, was convicted in 1986 of first-degree felony murder for the deaths of his wife and two young daughters in a house fire. He was sentenced to life in prison.

His conviction was overturned and he was released yesterday after spending 26 years in prison.

His first stop, the grave sites of his wife and daughters.

"It was a very emotional scene," said David Moran, a law professor and co-founder of the Innocence Clinic at the University of Michigan Law School, which fought for the release of 54-year-old David Lee Gavitt. Moran said 15-20 of Gavitt's family members also arrived to welcome him home.

Since Gavitt's conviction in 1986, fire science has advanced significantly. A fire science expert, John Lentini, reviewed some of the evidence in Gavitt's case for the Innocence Clinic:

He told the clinic that the burn patterns that had caused investigators to suspect arson weren't caused by an accelerant, like gasoline, but by flashover -- a then-misunderstood phenomenon in which a closed room fills with toxic gases and bursts into flames.

"In light of modern fire science, there is simply not one shred of credible evidence that the fire at the Gavitt residence was intentionally set," Lentini said in a 65-page affidavit the clinic presented last September to Judge Hoseth Kreeger.

As Frontline points out, there are several arson cases around the country being reviewed. And the case of Cameron Todd Willingham has caused experts to re-examine old assumptions:

These include assumptions about fire patterns on floors and v-shaped marks on walls, the identifying characteristics of an accelerant, and what happens to glass windows during a blaze. Gerald Hurst, who wrote a report discrediting the evidence used against Willingham in a last-minute death row appeal, declared: “One might well wonder how anyone could make so many critical errors in interpreting the evidence.”

Muskegon Public Safety Director Tony Kleibecker is returning to his roots at Michigan State University, accepting a university administrative position and leaving the city Aug. 31.

Kleibecker submitted his letter of resignation to Muskegon City Manager Bryon Mazade Wednesday morning, indicating he will end 11 years of service with the city. Kleibecker is leaving Muskegon to become assistant director for administration and communication with the MSU Police Department, he told his staff.

Jackson voters will be asked next Tuesday if they want to merge their city police and fire departments. It’s a decision that is dividing the southern Michigan city. Jackson, like many Michigan cities, is struggling to balance its budget. Tuesday’s vote to create a public safety department is a result of that.

Interim City Manager Warren Renando says Tuesday’s vote is about better allocating what little money the city has left to spend.